Data Sufficiency

x is an integer and x raised to any odd integer is greater than zero; is w - z greater than 5 times the quantity 7^(x - 1) - 5^x?

[1] z < 25 and w = 7^x.

[2] x = 4.


[spoiler]Source: https://www.platinumgmat.com[/spoiler]

IMO C

sanju09 wrote:x is an integer and x raised to any odd integer is greater than zero; is w - z greater than 5 times the quantity 7^(x - 1) - 5^x?

[1] z < 25 and w = 7^x.

[2] x = 4.


[spoiler]Source: https://www.platinumgmat.com[/spoiler]

C too

I have realized that for the last couple of days, Most of the times my answer is E

and one more E,

What is the OA ?

sanju09 wrote:x is an integer and x raised to any odd integer is greater than zero; is w - z greater than 5 times the quantity 7^(x - 1) - 5^x?

[1] z < 25 and w = 7^x.

[2] x = 4.


[spoiler]Source: https://www.platinumgmat.com[/spoiler]

What's the OA? I am getting A.

sanju09 wrote:x is an integer and x raised to any odd integer is greater than zero; is w - z greater than 5 times the quantity 7^(x - 1) - 5^x?

[1] z < 25 and w = 7^x.

[2] x = 4.


[spoiler]Source: https://www.platinumgmat.com[/spoiler]

Ofcourse "C".

Just received a PM demanding the OA for this:

This is clear that x is a positive integer; now, w and z are some numbers we don't know, with a question:

Is w - z > 5 {7^(x - 1) - 5^x}?

[1] The minimum x is 1, which minimizes w - z to just more than -18, and turns 5 {7^(x - 1) - 5^x} to be equal to -20. Anything more than -18 is always greater than -20. For other positive integers x, greater than 1, w - z will be positive, and 5 {7^(x - 1) - 5^x} always a negative, hence keeping the statement as always true. We do not need to fix a positive integer for x in order to make w - z > 5 {7^(x - 1) - 5^x} as true. This is sufficient

[2] This alone is always insufficient, as it never tells anything about w and z.


[spoiler]IMO happens to be the suggested OA in some cases.

IMO: A[/spoiler]

I'm getting A too